Dr. Mike Beck is lead scientist for The Nature Conservancy’s Global Marine Team.

I grew up on Long Island and spent nearly every summer day hanging around the beaches and marshes of Northport and the shores of New York, Connecticut, Rhode Island and Massachusetts with our family squeezed in our little 22’ sailboat. We endured a lot of storms in our time, but nothing like Sandy. The devastation to communities is breathtaking in its force and seeming indiscrimination.

But the fact is that the impacts were not indiscriminate; they were far worse in areas where we have built over and degraded coastal habitats.

As we put people and property evermore on top of coastlines, we destroy our first line of natural defense: dunes, marshes and oyster reefs. The evidence is clear. When we degrade our coasts, we add risk.

As rebuilding begins, we need to help orient communities sensibly and compassionately towards solutions that will reduce their long term risk. And if we use the rebuilding after past storms as a guide, then this short time is always when the worst and riskiest development choices get made.

But what can be done and do we know where to do it? The short answers are — we do know. Risk reduction always involves multiple solutions — green solutions, gray solutions, risk transfer, zoning, early warning and education. And this must all be combined to offer real benefits.

With regards to green — or nature-based — solutions, the science is clear. Wetlands and reefs can help protect us. They reduce wave energy, stabilize shorelines and slow erosion and add other risk reduction benefits too (like livelihoods).

When we choose to build over these first lines of defense, we put ourselves at much greater risk. And it is not just individuals who bear those costs — we all do.

Throughout New York and Connecticut, there remain just 40,000 acres of tidal wetlands, most of which continue to be degraded by development, the encroaching sea, and artificial defenses. If and when these marshes fully function, they could provide direct risk reduction benefits to 321,000 people, 1,700 miles of road, and structures (e.g., homes & businesses) with a replacement cost of $19 billion. And this only considers those people and property living right around these marshes in areas that can be reasonably affected by flooding.

Enhancing and protecting these marshes is critical and extraordinarily cost effective. We need to shore up these defenses while we consider and evaluate rebuilding defenses (green and gray) anew.

Moreover, we know how to restore and rebuild marshes and oyster reefs to enhance their coastal protection benefits. We are not just envisioning it; we are doing it in North Carolina, Alabama, Louisiana and Texas. There are on-line tools like coastalresilience.org that can help identify where people are most socially vulnerable and where property is most at risk from storm surge and sea level rise in New York and Connecticut. They also help identify solutions, like where marshes may offer the greatest risk reduction benefits to the most people.

And we must also consider future risks. For example, just a little bit of sea level rise (20 inches), which we are unfortunately well on track towards, will enable a Category 2 storm (like Sandy or Irene) to affect 47% more people and 73% more property.

This is a not so new world that we live in. These risks have always been real and we have known that they were growing — both because of climate change and our own coastal development choices. Now we have to face them. If we are going to do that cost effectively we are going to have to start adding green infrastructure in to our thinking. Fortunately, there science and demonstration projects show that they really work and there are leaders at COE, FEMA and NOAA that are developing greener approaches.

Finally, this is also going to mean that conservationists will have to change the way that they work; we cannot just focus on the marshes away from people that are less degraded and have higher diversity; we need to work right with and in front of some of our biggest populations — that is a real SeaChange.